Field of Invention
The present disclosure relates to technology for detecting inverters. More particularly, the present disclosure relates to a detecting device and a detecting method for detecting an output impedance angle of an inverter.
Description of Related Art
Inverters are power converting devices employing power electronics technology. Power can be converted from DC to AC by an inverter utilizing a suitable control method. When an output impedance of an inverter is pure inductive, an active power and a reactive power are decoupled. The active power of the inverter is mainly controlled by the phase of a voltage, and the reactive power of the inverter is mainly controlled by the amplitude of a voltage.
Based on power-transmission principles, a voltage source control type inverter that is grid-connected or a plurality of inverters connected in parallel usually use droop control. However, an output impedance of the inverter usually is inductive and resistive. Particularly when an inverter is connected to a low-voltage power grid, the active power and the reactive power are not decoupled. In this case, if a droop control is used, the coupling among the active power and the reactive power is higher.
If an output impedance angle of an inverter can be obtained and a rotation matrix is employed, the rotated active power and reactive power are decoupled; therefore, a droop control can be used. Hence, to control an inverter efficiently, the foregoing impedance must be obtained. However, there is no method at present which can automatically detect output impedance angles of inverters simply and accurately.
In view of the foregoing, problems and disadvantages are associated with existing products that require further improvement. However, those skilled in the art have yet to find a solution.